Isolation of Edwardsiella tarda from Swine

Edwardsiella tarda was isolated from the intestinal tract of a 2-month-old pig. This is the first reported isolation of Edwardsiella tarda from swine in the United States. Swine have been reported as potential carriers of Edwardsiella tarda, but pathogenicity of this organism for swine has not been determined. Although the pig had access to several farm ponds, the exact source of infection was not determined.     

Alkaline phosphatase isozymes in large intestines and large intestinal tumors of Fischer 344 rats

Eight electrophoretic forms of alkaline phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) were detected in butanol extracts of Fischer 344 rat large intestines. Seven of these isozymes have higher mobility than the small intestinal form(s) in non-denaturing polyacrylamide gel electrophoresis. These more mobile forms may be derived during extraction from more slowly migrating forms that are analogous to those forms found in the small intestine. Monoclonal antibody with specificity for a rat small intestinal isozyme cross-reacts with four of the large intestinal isozymes. This antibody does not cross-react with alkaline phosphatases from human or hog small intestine. Gel exclusion chromatography molecular weight estimates of rat intestinal forms range from 1.1 X 10(5) to 2.5 X 10(5). Alkaline phosphatase from two colon tumors obtained from azoxymethane treated rats appeared to be similar to an isozyme found in some normal rats, on the basis of electrophoretic mobility and cross-reactivity with the monoclonal antibody.     

Taxonomic and functional implications of stigma morphology in species ofCassia,Chamaecrista, andSenna (Leguminosae:Caesalpinioideae)

Two stigma forms occur inChamaecrista andSenna, but only one inCassia. In the common chambered form, a stigma pore is positioned on the reflexed style tip and is the entrance to a tapering chamber. The pore rim is fringed by hairs which vary in number, size, distribution and shape. In the alternative form the stigma is situated at the apex of the curved style and is crateriform. The crater rim is fringed by hairs of variable number and shape. The stigmatic hairs are predominantly unicellular and cutinized. Stigma and hair differences aid in the taxonomy of the genera. Their functions in pollination biology are discussed.     

A new class of membrane-associated calcium-binding proteins

Calcium ions act as modulators of many fundamental processes in eukaryotic cells. Although these processes apparently involve initial interactions between calcium ions and cell membranes, the identity of the putative membrane Ca²⁺-binding proteins has until recently been obscure. This article describes a recently discovered family of mammalian membrane proteins, of perhaps ancient origin, that may fulfil this function.     

Synthesis of factor II antigen by isolated perfused rat liver

Rat Factor II (prothrombin), isolated and purified by chromatography on Blue Dextran-agarose, was used to raise an antiserum in rabbits. On the basis of single radial immunodiffusion measurements. Factor II synthesis by isolated perfused rat liver amounted to 0.54 mg/300 cm² body surface area of the liver donor in 10 h. Corresponding measurements of Factor II coagulant activity revealed cumulative synthesis of 802 Iowa units. Coumadin added to the liver perfusate blocked production of Factor II coagulant activity, but did not change synthesis of the immunologically measured protein. In perfusions in which either heparin or citrate was used as anticoagulant, synthesis of albumin was not affected by the choice of anticoagulant but bile production and synthesis of Factor II were significantly less in citrate perfusions.     

Effects of group size on the responsiveness of zebrafish, Brachydanio rerio (Hamilton Buchanan), to alanine, a chemical attractant

Previous studies have examined the effects of grouping on the locating (search) phase of foraging and feeding behaviour in fishes. Few studies have examined whether schooling in fishes may facilitate individual foraging by enhancing a group's responsiveness to food odours. The purpose of the current study was to assess the effect of increasing group size on the responsiveness of zebrafish, Brachydanio rerio (Hamilton Buchanan), to L-alanine, an amino acid which is an important constituent of prey odours for many fishes. Based on the results of previous studies, either an increasing or decreasing linear relationship or a unimodal (convex or concave) relationship between responsiveness and group size was expected; the results, however, were bimodal. Groups of four fish were most responsive to alanine, as determined by the mean percentage of occurrences of fish in the area of a behavioural arena (an octagonal fluviarium) into which alanine was infused (at 10⁻³, 10⁻⁴, or 10⁻⁵ M). Groups of two, six and eight fish were significantly less responsive ( P < 0.05) than either groups of four fish or individual fish. The responses of groups of two, six and eight fish were not significantly different from each other.     

In vitro fertilization from co-cultured pollen tubes and female gametophytes of Douglas fir (Pseudotsuga menziesii)

 Our previous attempt on in vitro fertilization (IVF) in conifers resulted in pollen tube penetration of female gametophytes, but because of the rapid decline in egg viability, no further interaction occurred. In this report, we describe for the first time that IVF has been achieved in conifers. Using Douglas fir (Pseudotsuga menziesii), we describe a two-step process which involved induction of pollen tubes in culture followed by introduction of isolated female gametophytes at the tips of growing pollen tubes. Pollen tubes penetrated the introduced isolated female gametophytes at various places, but a number of tubes entered the egg cell through the neck cells similar to the in vivo condition. Under our current culture conditions, longevity of pollen tubes and eggs has been improved resulting in the release of sperms, fusion of gametes, and initial formation of the proembryo. Continued plasmolysis of the egg limited the number of successful gametic interactions. IVF has been accomplished in flowering plants in several ways, but the gametophyte-gametophyte IVF system described in this paper is unique. IVF offers a novel breeding technology that takes advantage of the sexual reproductive route. When coupled with hybridization and genetic transformation, IVF could result in the development of stable novel genotypes of economically superior trees. Received: 28 October 1997 / Accepted: 9 December 1997